1. Field of the Invention
The present invention relates to a communication slave that is used in a communication network system including a master and a plurality of communication slaves coupled through a pair of buses in a daisy chain manner.
2. Description of the Related Art
A protocol of a communication network that includes a master and a plurality of slaves coupled through a pair of buses in a daisy-chain manner includes a DSI (distributed system interface) and a SbW (safe by wire). The communication network needs to set an ID value to each of the slaves so that the master can perform a serial communication with the slaves. For example, JP-A-2003-152741 (corresponding to US 200310034883 A1) discloses a communication apparatus in which each of plurality of slave devices inserts a switch into a power source line that forms a bus, a master device sets ID values of the slave devices through the bus in order from the slave device close to the master device based on a connection order of the slave devices and ID values stored in the master device, and the slave device whose ID value is set turns on the switch one by one so that a next slave is coupled with the bus.
When the switch is inserted into the bus, an element such as a transistor for forming the switch needs to reduce an on-resistance value. Accordingly, a dimension of the switch may be increased, and a dimension of each of the slave, eventually, a dimension of the whole communication network system may be increased.